(CNN) -- Facebook's user base is nearly as large as the U.S. population and, for the first time, the site has turned a profit.

Facebook now has 300 million users -- almost as many as the population of the United States.

That was the double-barreled announcement Tuesday from Facebook CEO Mark Zuckerberg, who thanked the site's users for helping its online community cross the 300 million threshold. There are about 307 million people living in the United States, according to the U.S. Census Bureau.

"We're just getting started on our goal of connecting everyone," Zuckerberg wrote on the company's blog.

"Because we want to make it as easy and fast as possible for the world to connect, one of the things we think a lot about is how to make Facebook perform even faster and more efficiently as we grow," he wrote. "We face a lot of fun and important challenges that require rethinking the current systems for enabling information flow across the Web."

The social networking site, while popular with its exploding user base, has struggled to turn a profit.

But Zuckerberg said the company became profitable last quarter, beating its goal of getting out of the red by the end of 2010.

"This is important to us because it sets Facebook up to be a strong independent service for the long term," he wrote.

Over the past year, the social network has seen a challenge from Twitter, the popular micro-blogging site. Many bloggers see recent updates to Facebook's interface as copied from Twitter's stripped-down design.

As Facebook has grown, it also has drawn criticism from privacy groups like the American Civil Liberties Union, which says people on Facebook unwillingly give up personal information to advertisers and Facebook application developers.

She also told Fortune that a new approach to online advertising has helped Facebook's revenue grow throughout the recession.

"Our advertisements are very much part of the user experience," she said. "So the same way you can RSVP for an event on Facebook -- you know, a party your friend might throw -- you can RSVP for a movie premiere. And that's really a movie advertisement saying, 'Our movie is opening this weekend. Do you want to go?' "

After Zuckerberg's blog post went up Tuesday, more than 500 Facebook users commented, largely cheering him on.

"i [heart] facebook. mark, you are my hero!" one user wrote.

"Today the Internet, tomorrow the world," said another.

Technology blogs jumped on the news from Facebook, which was posted about 7 p.m. ET on Tuesday.

New technologies probably are helping Facebook keep its computer server costs down, which is important because Facebook stores a lot of data, he wrote. The site is effectively the largest photo-sharing site online, he said.